The bill would allow college athletes to accept endorsement money and earn income from the use of their names, images, and likenesses.

Earlier Wednesday, the NCAA board of governors sent a letter to Newsom urging him not to pass the legislation, calling it "unconstitutional."

The NCAA also said the bill could "upend" the competitive balance in college athletics while blurring the "critical distinction" between amateur and professional sports.

"If the bill becomes law and California's 58 NCAA schools are compelled to allow an unrestricted name, image, and likeness scheme, it would erase the critical distinction between college and professional athletics and, because it gives those schools an unfair recruiting advantage, would result in them eventually being unable to compete in NCAA competitions," the board wrote.

"These outcomes are untenable and would negatively impact more than 24,000 California student-athletes across three divisions. Right now, nearly half a million student-athletes in all 50 states compete under the same rules. This bill would remove that essential element of fairness and equal treatment that forms the bedrock of college sports."

On Monday, the California State Assembly unanimously voted to pass the bill, leaving the Senate and the governor as the final hurdles left to clear.